Application of timing advance command in wireless communication device in enhanced coverage mode

ABSTRACT

Embodiments disclosed herein relate to a method in a wireless communication device that operates in an enhanced coverage mode, the enhanced coverage mode comprising sequential repetition of messages sent from the wireless communication device to a network node. An example method includes: receiving a Timing Advance Command TAC from the network node; and adapting a time at which the TAC is applied, wherein a time difference between the time at which the TAC is applied and a time at which the TAC is received shall be greater than or equal to a specified time depending on a type of the used Radio Access Technology, such that application of the TAC does not occur during a period after a first subframe of a repeated uplink transmission till the end of the repeated uplink transmission.

TECHNICAL FIELD

Embodiments herein relate generally to a wireless communication system,a method in a wireless communication device, a method in a network node,a wireless communication device, and a network node. More particularly,the embodiments herein relate to the Application of Timing AdvanceCommands (TACs) in a wireless communication device in an EnhancedCoverage (CE) mode.

BACKGROUND

A wireless communication device, for example, an Evolved Machine TypeCommunication (eMTC) device or a Narrowband Internet of Things (NB-IoT)device, may operate in a coverage enhancement mode. The coverageenhancement mode is implemented by subsequent repetition of messagestransmitted between said device and a network node (e.g. eNodeB or basestation).

3GPP TS 36.133 V12.10.0, clause 7.3.2.1, specifies the following on whena timing advance command is to be applied: the UE shall adjust thetiming of its uplink transmission timing at sub-frame n+6 for a timingadvance command received in sub-frame n. The timing advance is, for anHD-FDD eMTC device, considered to have been received in the lastrepetition of the M-PDCCH, i.e., in subframe n. Thus, according to therule specified in 3GPP TS 36.133, the transmit timing is thereforeadjusted, in accordance to the received TAC, in subframe n+6.

SUMMARY

If conventional approaches are applied in the coverage enhancement mode,when TACs that have been received on the downlink are applied it ispossible that the reception performance of the network node woulddegrade. Particularly, if the TAC is applied after the onset (i.e., thefirst subframe) till the end of an uplink transmission, the accumulatedreference signals or message on the network node side will get corruptedby the linear phase change that results when the uplink transmit timingis changed as a result of the TAC. For instance, channel estimates thatmay be based on coherent averaging or filtering over successiverepetitions would be distorted, resulting in a degraded decodingperformance.

Hence there is a need for a new rule for Application of TAC in wirelesscommunication devices (for example, eMTC devices and NB-IoT devices)that operate in coverage enhancement mode.

An object of some of the techniques and apparatus disclosed herein istherefore to obviate at least one of the above disadvantages and toprovide improved communication between a wireless communication device,such as eMTC or NB-IoT, and a network node in a wireless communicationsystem.

According to an aspect of the presently disclosed techniques andapparatus, this object is achieved by a wireless communication systemincluding a wireless communication device and a network node, thewireless communication device operating in an enhanced coverage mode,the enhanced coverage mode comprising sequential repetition of messagessent from the wireless communication device to the network node. Thenetwork node includes: a sending unit configured to send a TAC to thewireless communication device. The wireless communication deviceincludes: a receiving unit configured to receive the TAC from thenetwork node; and an adapting unit configured to adapt a time at whichthe TAC is applied. The time difference between the time at which theTAC is applied and a time at which the TAC is received shall be greaterthan or equal to a specified time depending on the type of the usedRadio Access Technology, and application of the TAC shall not occurduring a period after a first subframe of a repeated uplink transmissionuntil the end of said repeated uplink transmission.

According to another aspect, the object is achieved by a method in awireless communication device that operates in an enhanced coveragemode, the enhanced coverage mode comprising sequential repetition ofmessages sent from the wireless communication device to a network node.The method includes: receiving a TAC from the network node; and adaptinga time at which the TAC is applied. A time difference between the timeat which the TAC is applied and a time at which the TAC is receivedshall be greater than or equal to a specified time depending on the typeof the used Radio Access Technology, and application of the TAC shallnot occur during a period after a first subframe of a repeated uplinktransmission until the end of said repeated uplink transmission.

According to yet another aspect, the object is achieved by a method in anetwork node in communication with a wireless communication device thatoperates in an enhanced coverage mode, the enhanced coverage modecomprising sequential repetition of messages sent from the wirelesscommunication device to the network node. The method includes:configuring the wireless communication device to transmit multipleuplink signals with different repetition periods; and configuring thewireless communication device to align the repetition periods byshifting in time at least one of start or end points of the repetitionperiods, such that an overlapping time of the repetition periods ismaximized.

According to yet another aspect, the object is achieved by a wirelesscommunication device that operates in an enhanced coverage mode, theenhanced coverage mode comprising sequential repetition of messages sentfrom the wireless communication device to a network node. The wirelesscommunication device includes: a receiving unit configured to receive aTAC from the network node; and an adapting unit configured to adapt atime at which the TAC is applied. A time difference between the time atwhich the TAC is applied and a time at which the TAC is received shallbe greater than or equal to a specified time depending on the type ofthe used Radio Access Technology, and application of the TAC shall notoccur during a period after a first subframe of a repeated uplinktransmission until the end of said repeated uplink transmission.

According to yet another aspect, the object is achieved by a networknode in communication with a wireless communication device that operatesin an enhanced coverage mode, the enhanced coverage mode comprisingsequential repetition of messages sent from the wireless communicationdevice to the network node. The network node includes a configuring unitconfigured to: configure the wireless communication device to transmitmultiple uplink signals with different repetition periods; and configurethe wireless communication device to align the repetition periods byshifting in time at least one of start or end points of the repetitionperiods, such that an overlapping time of the repetition periods ismaximized.

According to yet another aspect, the object is achieved by a wirelesscommunication device, wherein the wireless communication device isconfigured with hardware circuitry to carry out the above method forwireless communication device.

According to yet another aspect, the object is achieved by a networknode configured with hardware circuitry to carry out a configuration ofa wireless communication device for alignment of repetition periods.

According to yet another aspect, the object is achieved by acomputer-readable medium, carrying instructions, which, when executed bya processor, cause the processor to carry out any one of the abovemethods.

According to yet another aspect, the object is achieved by acomputer-program, accessible by a processor of a wireless communicationdevice or a network node, which the computer-program, when executed bythe processor, causes the processor to carry out any one of the abovemethods.

Embodiments herein afford many advantages, of which a non-exhaustivelist of examples is as follows:

The system performance is improved compared to applying the existingrule for application of timing advance. Particularly, distortion due toapplication of timing advance during an uplink transmission is avoided.

The alignment between the repetition periods of multiple uplink signalsenables the wireless communication device to apply the received TACcommand to adjust its uplink transmit timing immediately or with ashorter delay after the end of the repetition period of each uplinksignal and as soon as the after the occurrence of the time resource.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments herein will now be further described in more detail inthe following detailed description by reference to the appended drawingsillustrating the embodiments and in which:

FIG. 1 is a schematic diagram showing one embodiment of a wirelesscommunication system.

FIG. 2 is a schematic block diagram showing one embodiment of a wirelesscommunication device.

FIG. 3 is a schematic block diagram showing one embodiment of a networknode in communication with the wireless communication device.

FIG. 4 is a flow chart showing one embodiment of a method in thewireless communication device.

FIG. 5 is a flow chart showing one embodiment of a method in the networknode.

FIG. 6 is a schematic diagram showing one embodiment of operations inthe wireless communication device.

FIG. 7 is a flow chart showing one embodiment of a method in thewireless communication device.

FIG. 8 is a schematic diagram showing one embodiment of aligningoperations in the wireless communication device; wherein (a) shows atleast two uplink signals whose repetition periods partly overlap witheach other in time; (b) and (c) show the aligned signals.

FIG. 9 is a schematic block diagram showing one embodiment of a networknode.

FIG. 10 is a schematic block diagram showing one embodiment of awireless communication device.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments herein will be described in detail hereinafter withreference to the accompanying drawings, in which embodiments are shown.These embodiments herein may, however, be embodied in many differentforms and should not be construed as being limited to the embodimentsset forth herein. The elements of the drawings are not necessarily toscale relative to each other. Like numbers refer to like elementsthroughout.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” “comprising,”“includes” and/or “including” when used herein, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meanings as commonly understood. Itwill be further understood that a term used herein should be interpretedas having a meaning consistent with its meaning in the context of thisspecification and the relevant art and will not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

The present technology is described below with reference to blockdiagrams and/or flowchart illustrations of methods, nodes, devices(systems) and/or computer program products according to the presentembodiments. It is understood that blocks of the block diagrams and/orflowchart illustrations, and combinations of blocks in the blockdiagrams and/or flowchart illustrations, may be implemented by computerprogram instructions. These computer program instructions may beprovided to a processor, controller or controlling unit of a generalpurpose computer, special purpose computer, and/or other programmabledata processing apparatus to produce a machine, such that theinstructions, which execute via the processor of the computer and/orother programmable data processing apparatus, create means forimplementing the functions/acts specified in the block diagrams and/orflowchart block or blocks.

Accordingly, the present technology may be embodied in hardware and/orin software (including firmware, resident software, micro-code, etc.).Furthermore, the present technology may take the form of a computerprogram product on a computer-usable or computer-readable storage mediumhaving computer-usable or computer-readable program code embodied in themedium for use by or in connection with an instruction execution system.In the context of this document, a computer-usable or computer-readablemedium may be any medium that may contain, store, communicate,propagate, or transport the program for use by or in connection with theinstruction execution system, apparatus, or device.

It should be noted that resource releasing methods performed by the BSand the UE, based on different resource releasing reasons, will beschematically illustrated in the following figures. It should noted thatwhile the one or more methods shown herein, for example, in the form ofa flow chart or flow diagram, are shown and described as a series ofsteps, for purposes of simplicity of explanation, it is to be understoodand appreciated that the methods are not limited to the illustrated ordescribed order of steps, unless the context clearly indicatesotherwise, as some steps may, in accordance therewith, occur in adifferent order and/or concurrently with other acts from that shown anddescribed herein. It will be appreciated for the person skilled in theart to implement the alteration, modification and variant of the methodswithout departing from the spirit and scope of this disclosure, whichmeans different permutation or combination of the steps corresponding tothe methods described in different figures, will be apparent when theperson skilled in the art after reading the disclosure.

The embodiments herein provide a new rule for Application of TAC inwireless communication devices (for example eMTC devices and NB-IoTdevices) that operate in coverage enhancement mode. Some technicalcontexts of the embodiments herein are introduced firstly.

eMTC

eMTC features specified in 3GPP technical contributions identified by3GPP as contribution documents 3GPP RP-152024 and 3GPP R1-157926 includea low-complexity user equipment (UE) category called UE category M1 (orCat-M1 for short) and coverage enhancement techniques, CE modes A and B,that can be used together with UE category M1 or any other LTE UEcategory.

All eMTC features, for both Cat-M1 and CE modes A and B, as defined in3GPP TS 36.133 V12.7.0, Section 7.1.2, operate using a reduced maximumchannel bandwidth compared to normal LTE. The maximum channel bandwidthin eMTC is 1.4 MHz, whereas it is up to 20 MHz in normal LTE. The eMTCUEs are still able to operate within the larger LTE system bandwidth,generally without problems. The main difference compared to normal LTEUEs is that the eMTCs can only be scheduled with 6 physical resourceblocks (PRBs) at a time, where each of these PRBs has a bandwidth of 180kHz.

In CE modes A and B, the coverage of physical channels is enhancedthrough various coverage enhancement techniques, the most importantbeing repetition or retransmission. In its simplest form, this meansthat the 1-millisecond subframe to be transmitted is repeated a numberof times, e.g., just a few times if a small coverage enhancement isneeded or hundreds or thousands of times if a large coverage enhancementis needed.

NB-IoT

The objective of the Narrow Band Internet-of-things (NB-IoT) initiativeof the 3GPP is to specify a radio access for cellular internet of things(IoT), based to a great extent on a non-backward-compatible variant ofE-UTRA (LTE), that addresses improved indoor coverage, support formassive number of low throughput devices, low delay sensitivity,ultra-low device cost, low device power consumption and (optimized)network architecture.

The NB-IoT carrier BW (Bw2) is 200 KHz. Examples of the operatingbandwidth (Bw1) of LTE, in contrast, are 1.4 MHz, 3 MHz, 5 MHz, 10 MHz,15 MHz, 20 MHz, etc.

NB-IoT radio access supports three different modes of operation:

-   -   1. ‘Stand-alone operation’ utilizing, for example, the spectrum        currently being used by GERAN systems as a replacement of one or        more GSM carriers. In principle this mode of operation can use        any carrier frequency which is neither within the carrier of        another co-located (or overlapping) system nor within the guard        band of another system's operating carrier. The other system can        be another NB-IoT operation or any other radio access technology        (RAT), e.g., LTE.    -   2. ‘Guard band operation’ utilizing the unused resource blocks        within a LTE carrier's guard-band. The term guard band may also        interchangeably be called guard bandwidth. As an example, in the        case of an LTE BW of 20 MHz (i.e., Bw1=20 MHz or 100 RBs), the        guard band operation of NB-IOT can be placed anywhere outside        the central 18 MHz but within 20 MHz LTE BW.    -   3. ‘In-band operation’ utilizing resource blocks within a normal        LTE carrier. The in-band operation may also interchangeably be        called in-bandwidth operation. More generally the operation of        one RAT within the BW of another RAT is also called in-band        operation. As an example, in a LTE BW of 50 RBs (i.e., Bw1 of 10        MHz or 50 RBs), NB-IoT operation over one resource block (RB)        within the 50 RBs is called in-band operation.

In NB-IoT, the downlink transmission is based on OrthogonalFrequency-Division Multiplexing (OFDM), with 15 kHz subcarrier spacingfor all the scenarios: standalone, guard-band, and in-band. For uplinktransmission, both multi-tone transmissions, based on single-carrierFrequency-Division Multiple Access (SC-FDMA), and single tonetransmission are supported. This means that the physical waveforms forNB-IoT in downlink and also partly in uplink are similar to those inlegacy LTE.

In the downlink design, NB-IoT supports both master informationbroadcast and system information broadcast which are carried bydifferent physical channels. For in-band operation, it is possible forNB-IoT UE to decode NB-PBCH (also referred to as NPBCH) without knowingthe legacy PRB index. NB-IoT supports both downlink physical controlchannel (NB-PDCCH, also referred to as NPDCCH) and downlink physicalshared channel (PDSCH, also referred to as NPDSCH). The operation modeof the NB-IoT radio access must be indicated to the UE, and currently3GPP consider indication by means of NB-SSS (also referred to as NSSS),NB-MIB (carried on NB-PBCH, also referred to as NPBCH), or perhaps otherdownlink signals.

The reference signals to be used in NB-IoT have not yet been specified.However, it is expected that the general design principle will followthat of legacy LTE. Downlink synchronization signals will most likelyconsist of primary synchronization signal (NB-PSS, also referred to asNPSS) and secondary synchronization signal (NB-SSS, also referred to asNSSS).

Half-Duplex Operation

In half-duplex (HD) operation, or more specifically half-duplex FDD(HD-FDD) operation, the uplink (UL) and downlink (DL) transmissions takeplace on different paired carrier frequencies but not simultaneously intime in the same cell. This means that the uplink and downlinktransmissions take place in different time resources. Examples of a timeresource are symbols, time slots, subframes, transmission time intervals(TTIs), interleaving times, etc. In other words, uplink and downlink(e.g., subframes) do not overlap in time. The number and location ofsubframes used for downlink, uplink, or unused subframes can vary on aframe-to-frame basis, or on a basis of multiple frames. For example, inone radio frame (say frame #1), subframes #9, #0, #4 and #5 may be usedfor downlink, while subframes #2 and #7 are used for uplinktransmission. But in another frame (say frame #2), subframes #0 and #5are used for downlink and subframes #2, #3, #5, #7 and #8 are used foruplink transmission.

Timing Advance

In order to preserve orthogonality in uplink SC-FDMA transmissions, theuplink transmissions from multiple user equipments (UEs) in LTE need tobe time aligned at a receiver, such as a base station, e.g., an LTEeNode B or the like. This means that the transmit timing of those UEsthat are under the control of the same eNode B should be adjusted toensure that their received signals arrive at the eNode B receiver atapproximately the same time. More specifically, their received signalsshould arrive well within the cyclic prefix (CP), where the normal CPlength is about 4.7 μs. This ensures that the eNode B receiver is ableto use the same resources, i.e., the same Discrete Fourier Transform(DFT) or Fast Fourier Transform (FFT) resource, to receive and processthe signals from multiple UEs.

The uplink timing advance (TA) is maintained by the eNode B throughtiming advance commands, also referred to as timing alignment commands,sent to the UE based on measurements on uplink transmissions from thatUE. For example, the eNode B measures a two-way propagation delay orround-trip time for each UE, to determine the value of the TA requiredfor that UE.

For a timing advance command received on subframe n, the correspondingadjustment of the uplink transmission timing is applied by the UE fromthe beginning of subframe n+6. The timing advance command indicates thechange of the uplink timing relative to the current uplink timing of theUE transmission as multiples of 16 Ts, where Ts=32.5 ns and is calledthe “basic time unit” in LTE.

In the case of random access response messages transmitted by the eNodeB's, an 11-bit timing advance command (TA) for a Timing Advance Group(TAG) indicates NTA values by index values of TA=0, 1, 2, . . . , 1282,where an amount of the time alignment for the TAG is given by NTA=TA×16.NTA is defined above in section “Alignment of E-UTRA TDD measurementgaps with particular subframe offsets”.

In other cases, a 6-bit timing advance command (TA) for a TAG indicatesadjustment of the current NTA value, NTA,old, to the new NTA value,NTA,new, by index values of TA=0, 1, 2, . . . , 63, whereNTA,new=NTA,old+(TA−31)×16. Here, adjustment of NTA value by a positiveor a negative amount indicates advancing or delaying the uplinktransmission timing for the TAG by a given amount respectively.

Timing advance updates are signaled by the evolved Node B (eNB) to theUE in MAC PDUs.

Coverage Enhancements

The path loss between IoT device and the base station can be very largein some scenarios, such as when the device is used as a sensor ormetering device located in a remote location such as in the basement ofthe building. In such scenarios, the reception of the signal from basestation may be very challenging. For example, the path loss can be worseby 20 dB, compared to normal operation. In order to cope with suchchallenges, the coverage in uplink and/or in downlink has to besubstantially enhanced with respect to the normal coverage (alsoreferred to as legacy coverage). This is realized by employing one orseveral advanced techniques in the UE and/or in the radio network nodefor enhancing the coverage. Some non-limiting examples of such advancedtechniques include transmit power boosting, repetition of transmittedsignal, applying additional redundancy to the transmitted signal, use ofadvanced/enhanced receiver architectures, etc. In general, whenemploying such coverage enhancing techniques, the IoT radio access isregarded to be operating in ‘coverage enhancing mode’ or coverageextending mode.

When coverage enhancement is provided by means of transmissionrepetitions, the maximum number of repetitions for PDSCH and PUSCH,respectively, for coverage enhancement modes A and B are given bycell-specific broadcasted parameters:

-   -   pdsch-maxNumRepetitionCEmodeA (up to 32 repetitions),    -   pdsch-maxNumRepetitionCEmodeB (up to 2048 repetitions),    -   pusch-maxNumRepetitionCEmodeA (up to 32 repetitions),    -   pusch-maxNumRepetitionCEmodeB (up to 2048 repetitions).

The exact number of repetitions to use by a particular wirelesscommunication device is signaled dynamically via the downlink controlinformation (DCI), which is carried over the downlink control channelM-PDCCH. This channel, too, may be repeated according to a specificrepetition number individually configured for each wirelesscommunication device:

-   -   mPDCCH-NumRepetition (up to 256 repetitions).        When the wireless communication device transmits on the uplink        control channel, it may use repetitions as individually        configured by the network node:    -   pucch-NumRepetitionCE-Format1 (up to 8 (mode A) or 32 (mode B)        repetitions),    -   pucch-NumRepetitionCE-Format2 (up to 8 (mode A) or 32 (mode B)        repetitions).        Hence, depending on the coverage, wireless communication devices        may apply different number of repetitions.

A low complexity UE (e.g., a UE with one receiver, or “Rx”) may also becapable of supporting enhanced coverage mode of operation. The coveragelevel of the UE with regard to a cell may be expressed in terms of asignal level, such as signal quality, signal strength or path loss, withregard to that cell.

Example Embodiments

The several embodiments of methods and apparatus described hereinconcern a rule wherein the wireless communication device avoids applyingthe TAC during an ongoing repetition period. That is, applying the TACshall avoid a repetition period which is started and not finished.

FIG. 1 is a schematic diagram showing one embodiment of a wirelesscommunication system 100 in which embodiments herein may be implemented.The wireless communication system 100 may in some embodiments apply toone or more Radio Access Technologies (RAT) such as, for example, LTE,LTE Advanced, WCDMA, GSM, Worldwide Interoperability for MicrowaveAccess (WiMAX), or any other radio access technology.

In some embodiments, the wireless communication system 100 may includeat least one wireless communication device 101 and at least one networknode 102. However, the embodiments herein do not limit the number of thewireless communication device 101 and the network node 102.

In some embodiments, the wireless communication device 101 operates inan enhanced coverage mode in which the wireless communication device 101transmits a sequential repetition of messages to the network node 102 inone or more uplink channels. In another embodiment, the network node 102also operates in an enhanced coverage mode in which the network node 102transmits a sequential repetition of messages to the network node 102 inone or more downlink channels. However, there is no need for the networknode 102 to operate in an enhanced coverage mode.

The network node 102 may adjust the uplink transmitting timing of thewireless communication device 101 by sending a Timing Advance Command(TAC) to the wireless communication device 101. The wirelesscommunication device 101 may adapt a time at which the TAC is appliedaccording to a new rule. In one embodiment, the new rule can beexpressed as: a time difference between the time at which the TAC isapplied and a time at which the TAC is received shall be greater than orequal to a specified time depending on the type of the used Radio AccessTechnology; and application of the TAC shall not occur after a firstsubframe till the end of any repeated uplink transmission.

In LTE, the above specified time is defined as 6 subframes. Thus, inthis context the wireless communication device 101 shall adjust thetiming of its uplink transmission timing at subframe n+6 or later thansubframe n+6 for a timing advance command received in subframe n.Furthermore, the uplink transmission timing adjustment of the wirelesscommunication device 101 does not occur after the onset (i.e., the firstsubframe) till the end of any one repeated uplink transmission.

The system performance is improved compared to applying the existingrule for application of timing advance. Particularly, distortion due toapplication of timing advance during an uplink transmission is avoided.

In one embodiment, the new rule which the UE has to comply with andimplement may, for instance, be captured for LTE in the specification(for example 3GPP 36.133) as follows.

-   -   When no uplink repetition period has been configured, or an        uplink repetition period has been configured but with a single        transmission (R=1), the UE shall adjust the timing of its uplink        transmission timing at sub-frame n+6 for a timing advance        command received in sub-frame n.    -   When an uplink repetition period has been configured for which        the repetition R>1, the UE shall:        -   adjust the timing of its uplink transmission timing at            sub-frame n+6 for a timing advance command received in            sub-frame n, provided that subframe n+6 does not fall within            an ongoing uplink repetition period; otherwise        -   adjust the timing of its uplink transmission timing at            sub-frame k, where subframe k represents the onset of the            first uplink repetition period for which k≥n+6.

FIG. 2 is a schematic block diagram showing an example embodiment of thewireless communication device 101. In some embodiments, as illustratedin FIG. 2, the wireless communication device 101 may include, but is notlimited to, a receiving unit 201 and an adapting unit 202. The receivingunit 201 may be configured to receive the TAC from the network node, forexample, at subframe n; and the adapting unit 202 may be configured toadapt a time at which the TAC is applied, according to the abovementioned new rule proposed herein.

In some embodiments, the adapting unit 202 may include, but is notlimited, to a determining unit 203, a deciding unit 204, and an applyingunit 205. Furthermore, the embodiments herein are not limited to thisembodiment. In other embodiments, a determining unit 203, a decidingunit 204, and an applying unit 205 of the wireless communication device101 are included in the adapting unit 202.

In some embodiments, the determining unit 203 may be configured todetermine a subframe n at which the TAC is received, and determine atime difference, in the form of the number of subframes m, between thesubframe n and a first subframe k of a first repeated uplinktransmission. The deciding unit 204 may be configured to decide whetherapplication of the TAC in subframe n+q would occur after the onset(first subframe) till the end of the first repeated uplink transmissionand output a respective decision, if q is used to stand for the abovementioned specified delay in the form of the number of subframes. Theapplying unit 205 may be configured to receive the decision from thedeciding unit 204 and apply the TAC according to the above decision.

More details regarding the wireless communication device 101 will bedescribed in connection to FIGS. 6-8 hereinafter.

FIG. 3 is a schematic block diagram showing one embodiment of thenetwork node 102 in communication with the wireless communication device101. In some embodiments, as shown in FIG. 3, the network node 102 mayinclude, but is not limited to, a TAC generating unit 303 and a sendingunit 301. The TAC generating unit 303 may be configured to generate aTAC to be used by the wireless communication device 101, and the sendingunit 301 may be configured to send the generated TAC to the wirelesscommunication device 101. Note that, the embodiments herein are notlimited to this embodiment. In other embodiments, the network node 102does not include a TAC generating unit. In this case, the TAC may begenerated by another node and sent to the network node 102, and thesending unit 301 of the network node 102 may send the received TAC tothe wireless communication device 101.

In some embodiments, the network node 102 may include a configuring unit302 which may configure the wireless communication device 101 totransmit multiple uplink signals with different repetition periods, andconfigure the wireless communication device 101 to align the repetitionperiods by shifting in time at least one of start or end points of therepetition periods, such that an overlapping time of the repetitionperiods is maximized or single transmission of the multiple uplinksignals is minimized.

FIG. 4 is a flow chart showing one embodiment of a method 400 in thewireless communication device 101. In some embodiments, the wirelesscommunication device 101 operates in an enhanced coverage mode, theenhanced coverage mode comprising sequential repetition of messages sentfrom the wireless communication device 101 to the network node 102.

In some embodiments, the method may include, but is not limited to, thefollowing steps illustrated in FIG. 4. In step S401, the wirelesscommunication device 101 may receive a Timing Advance Command (TAC) fromthe network node 102. In step S402, the wireless communication device101 may adapt a time at which the TAC is applied according the new ruleproposed herein. According to the new rule, a time difference betweenthe time at which the TAC is applied and a time at which the TAC isreceived shall be greater than or equal to a specified time depending onthe type of the used Radio Access Technology; and application of the TACshall not occur after a first subframe till the end of any repeateduplink transmission.

The wireless communication device 101 may be configured to transmit onlyone uplink repeated signal or at least two uplink repeated signals. Thewireless communication device 101 may transmit the at least two uplinkrepeated signals in at least two uplink channels. The repetition periodsof the at least two uplink signals may or may not overlap with eachother in time.

FIG. 5 is a flow chart showing an example of a method 500 in the networknode 102. In step S501, configuring unit 302 may configure the wirelesscommunication device 101 to transmit multiple uplink signals withdifferent repetition periods. In step S502, the configuring unit 302 ofthe network node 102 may configure the wireless communication device 101to align the repetition periods by shifting in time at least one ofstart or end points of the repetition periods, such that an overlappingtime of the repetition periods is maximized or single transmission ofthe multiple uplink signals is minimized.

FIG. 6 is a schematic diagram showing an example of operations in thewireless communication device 101, which describes a method in wirelesscommunication device of adapting application of TAC when configured totransmit one signal with repetition during repetition period. In theillustrated scenario, it is assumed that the UE is configured totransmit one type of uplink signal with certain number of repetitions(N0) over a certain time period (T0). For example, over T0 the UE willtransmit only one of the uplink signals. Examples of an uplink signalcan be PUSCH, RACH, M-PUCCH, NB-IoT PUSCH, etc.

For example, the UE can be configured to transmit only PUSCH with 32repetitions over 32 consecutive uplink time resources, e.g. 32subframes, 32 TTIs, 32 interleaving time periods, etc. This correspondsto a repetition period (T0) of 32 ms for FDD. However, T0 in case ofHD-FDD and TDD will be longer than 32 ms; the actual value of T0 woulddepend on the number of uplink subframes available in a frame.

In this case, the UE shall apply the TAC received from the network nodeat the start (for example first subframe) of T0 of the uplink signal,but not earlier than in n+X time resources. This means the UE shall notapply the received TAC during a period after the first subframe of T0till the end of T0, but rather apply it in the first time resource inwhich T0 starts, such as the first uplink subframe within T0. The timeresource “n” denotes the time resource in which the UE receives TAC and“X” represents a specified delay. The value of X may depend on the typeof RAT. As an example X=6 subframes in LTE. The value of X allows the BSto adjust its receiver parameter and also the UE to process the receivedTAC command from the network node.

FIG. 6 illustrates a non-limiting example scenario, where the wirelesscommunication device 101 (e.g. UE, eMTC device, NB-IoT device) receivesa TAC during the downlink repetition period that ends in subframe n.Depending on whether the number of subframes m between the downlinkrepetition period and the first uplink repetition period is less than orat least equal to q, where q is 6 in legacy LTE, the wirelesscommunication device 101 either postpones the application of the TAC tothe onset (for example first subframe) of the second repetition period(UL repetition period 2) or applies it at the onset (for example firstsubframe k) of the first repetition period (UL repetition period 1).

It is assumed in this example that m+r+Δ≥q, where r is the number ofrepetitions in uplink repetition period 1, and Δ is the number ofsubframes between end of uplink repetition period 1 and onset of uplinkrepetition period 2, e.g. downlink repetition period in between, or somescheduling-related gap in the transmission. Had m+r+Δ, not fulfilledbeing equal to or larger than q, the application of TAC would have beenfurther postponed, until the onset of an uplink repetition periodstarting in a subframe s for which s≥n+q.

FIG. 7 is a flow chart showing one example of a method 700 in thewireless communication device 101, which describes a flow chart for themethod described in FIG. 6. In some embodiments, the flow chart in FIG.7 can be implemented as the step S402 shown in FIG. 4 by the adaptingunit 202 of the wireless communication device 101 shown in FIG. 2.

After receiving a TAC from the network node 102, in step S701, thewireless communication device 101 determines the time at which the TACis received. For example, the determining unit 203 of the wirelesscommunication device 101 may determine that the TAC is received insubframe n, where n is defined as the last subframe in a repetitionperiod.

In step S702, the wireless communication device 101 determines a timedifference, in the form of the number of subframes m, between thesubframe n and a first subframe k of a first repeated uplinktransmission T0. For example, the determining unit 203 of the wirelesscommunication device 101 may determine the number of subframes m thatwill pass from the receiving of TAC till onset (first frame) of uplinkrepetition period 1 shown in FIG. 6.

In step S703, the wireless communication device 101 may decide whetherapplication of the TAC in subframe n+q would occur after the firstsubframe till the end of the uplink repetition period 1, wherein qstands for the specified time depending on the type of the used RadioAccess Technology RAT, in the form of the number of subframes. Forexample, the deciding unit 204 in the wireless communication device 101may perform this deciding step by comparing m and q, for example q=6 inlegacy LTE.

If this number m is greater than or equal to the number q, (S703: Yes),in step S704, the wireless communication device 101 will apply the TACin the first uplink transmission period. For example, the applying unit205 of the wireless communication device 101 may apply the TAC at thefirst subframe k of the first repeated uplink transmission shown asuplink repetition period 1.

If on the other hand m is less than q (S703: No), in step S705, thewireless communication device 101 may postpone the application of theTAC until the next uplink repetition period whose onset (first frame s)satisfies s≥n+q. For example, the applying unit 205 of the wirelesscommunication device 101 may apply the TAC at the first subframe s ofthe second repeated uplink transmission shown as uplink repetitionperiod 2 or any other repetition period whose first frame s satisfiess≥n+q.

Although FIGS. 6 and 7 are described by the example in which thewireless communication device 101 is configured to transmit only oneuplink repeated signal, the same method is suitable for the example inwhich the wireless communication device 101 is configured to transmit atleast two uplink signals not overlapping with each other in time.

As described in the above embodiments, in the proposed TAC applyingmethod herein, the TAC shall be applied not earlier than a specifieddelay from the reception of TAC and shall not be applying during anongoing repetition period. That is, a time difference between the timeat which the TAC is applied and a time at which the TAC is receivedshall be greater than or equal to a specified time depending on the typeof the used Radio Access Technology, and application of the TAC shallnot occur during a period after a first subframe of a repeated uplinktransmission till the end of said repeated uplink transmission. Forexample, the application of the TAC shall not occur during a periodafter a first subframe of uplink repetition period 1 until the end ofuplink repetition period 1, and the application of the TAC shall notoccur during a period after a first subframe of uplink repetition period2 till the end of uplink repetition period 2, and so on.

The new rule proposed herein is applicable to the case when the wirelesscommunication device is configured to transmit at least two uplinksignals whose repetition periods partly overlap with each other in time.In one embodiment, the method in wireless communication device ofadapting application of TAC when configured to transmit at least tworepeated uplink signals during overlapping repetition periods isproposed herein.

In this case the disclosed rule requires the wireless communicationdevice to apply the received TAC at the start of the repetition periodof any of the uplink signals that does not overlap in time with therepetition period of any of the other uplink signals.

As described in FIGS. 6 and 7, the TAC also in this case should beapplied not earlier than in n+q time resource e.g. q=6 subframes forLTE. This technique is further elaborated with an example comprising 2uplink signals configured with repetitions over overlapping repetitionperiods. However, the technique is applicable to any number of uplinksignals configured to transmit with certain repetitions over at leastpartly overlapping time.

Assume that the wireless communication device 101 is configured with onefirst signal with a certain repetition over a first repetition period(T1) and at least a second signal with a certain repetition over asecond repetition period (T2). It is further assumed that T1 and T2 atleast partly overlap in time. For example, the wireless communicationdevice 101 can be configured to transmit the first signal such as PUSCHwith 32 repetitions over T1. The wireless communication device 101 mayalso be configured to transmit the second signal such as random accesswith certain number of repetitions during T2. In yet another embodimentit is assumed that the UE performs RA during T0 with one transmissionattempt, i.e., an original transmission only, without repetitions.

The wireless communication device 101 may initiate RA transmissionautonomously or in response to a request received from the network node102. The UE may perform RA transmission for one or more of the followingreasons e.g., for performing or enabling eNB to perform positioningmeasurement such as TA, UE Rx-Tx time difference, eNB Rx-Tx timedifference, etc.

According to some embodiments of the disclosed method the wirelesscommunication device 101 behavior is as follows; the wirelesscommunication device 101:

-   -   is not allowed to apply any of the received TACs to adjust        uplink transmit timing during ongoing uplink repetition periods        of any of the uplink signals but is allowed to autonomously        adjust its uplink transmit timing when no repetition period is        ongoing, such as:    -   in a time resource occurring not earlier than n+X time resource        (for example n+q in subframe) and in a time resource occurring        at the start of the repetition period of a signal with the        earliest starting time compared to the starting times of        repetition periods of other signals overlapping in time or    -   in a time resource occurring not earlier than n+X time resource        (for example n+q in subframe) and in a time resource occurring        after the end of the repetition period of a signal with the        latest terminating time compared to the terminating times of        repetition periods of other signals overlapping in time.

In some embodiments, the relative alignment between the repetitionperiods (Ta, Tb) (and possibly when to perform the establishment of therelations between the repetition periods) should be affected by thedelay n+X. However, in other embodiments, the relative alignment betweenthe repetition periods (Ta, Tb) (and possibly when to perform theestablishment of the relations between the repetition periods) shouldnot be affected by the delay n+X.

The above UE behavior is elaborated with an example where the first andsecond signal transmission have at least partly overlapping repetitionperiods of T1 and T2 respectively. Assume that T1 starts before T2 andT1 ends before T2, i.e., T2 terminates after T1. In this example, the UEis not allowed to apply any TAC command to adjust its uplink timing fromthe start of T1 and until the end of T2. However, the UE is allowed toapply the received TAC command to adjust or change its uplink transmittiming in a time resource occurring just before T1 or just after T2provided that time resource occurs not earlier than n+X (for example n+qin subframe, q=6 subframes for LTE) time resource.

FIG. 8 is a schematic diagram showing an example of aligning operationsin the wireless communication device 101. The aligning operations may beperformed by the aligning unit 207 of the wireless communication device101. In some embodiments, the wireless communication device 101 furtherincludes a transmitting unit 206. As shown in FIG. 8(a), thetransmitting unit 206 may be configured to transmit at least two uplinksignals whose repetition periods partly overlap with each other in time.For example, the two uplink signals with different repetition periodsTa, Tb can be transmitting in uplink channel a and uplink channel brespectively.

The aim of this approach is to allow alignment between the repetitionperiods of multiple uplink signals as much as possible. This alignmentenables the wireless communication device 101 to apply the received TACcommand to adjust its uplink transmit timing immediately or with ashorter delay after the end of the repetition period of each uplinksignal and as soon as the after the occurrence of the time resource n+X.In other words, the overlapping time of the repetition periods (Ta, Tb)is maximized or single transmission of uplink signals is minimized.Examples are shown below.

In some embodiments, the wireless communication device 101 may adjust atleast two uplink signals with certain number of repetitions by ensuringthat their repetition periods are related by one or more of thefollowing relations:

-   -   Their repetition periods start at the same time e.g. in the same        time resource such as in the same subframe, as shown in FIG.        8(b);    -   Their repetition periods end at the same time e.g. in the same        time resource such as in the same subframe, as shown in FIG.        8(c);    -   Their repetition periods start within a certain time duration        (Δ1) e.g. within a number X of time resources such as 5        subframes;    -   Their repetition periods end within a certain time duration (Δ2)        e.g. within a number Y of time resources such as 10 subframes.

Furthermore, although this approach is described as taking place in thewireless communication device 101, a similar method can be implementedin a node, which can be a network node 102 in communication with thewireless communication device 101, which can also be a user equipment(UE). In other embodiments, a method in a node of configuring uplinksignals with repetitions to enhance UE uplink TAC application procedureis described herein.

In this method, for example shown in S502 of FIG. 5, a network node 102may configure the wireless communication device 101 with at least twouplink signals with certain number of repetitions by ensuring that theirrepetition periods are related by one or more of the followingrelations:

-   -   Their repetition periods start at the same time e.g. in the same        time resource such as in the same subframe;    -   Their repetition periods end at the same time e.g. in the same        time resource such as in the same subframe;    -   Their repetition periods start within a certain time duration        (Δ1) e.g. within a number X of time resources such as 5        subframes;    -   Their repetition periods end within a certain time duration (Δ2)        e.g. within a number Y of time resources such as 10 subframes.

The above relations between the repetition periods are established orensured by the node if it is a UE when it is determined by the UE thatthe TAC has to be applied by the UE, e.g. when the UE has received orexpected to receive at least one TAC from the network node. The aboverelations between the repetition periods are established or ensured bythe node if the node is a network node when it is determined by the NWnode that the UE is expected to be configured or is configured with atleast one TAC for adjusting the uplink timing of the UE. This can bedetermined for example when the NW node has identified that thepropagation delay between the UE and the NW node is larger than acertain threshold, e.g., 3 μs. The above relations between therepetition periods can be implementation specific, pre-defined orconfigured at the UE by the network node.

For example, assume that the UE is configured by the network node totransmit the first signal, PUSCH, with a certain repetition over therepetition period of T1. During T1 the network node may further requestthe UE to transmit second signal, random access, with a certainrepetition over the repetition period of T2. As a special case, therepetition for the second signal may be 1, i.e., R=1. In one exemplaryimplementation, the UE may be configured to transmit RA with allrepetitions by the end of T1, i.e., T2 ends in the single and last timeresource just before or after the T1. By scheduling T2 at the end of T1,the UE is allowed to adjust its uplink transmit timing immediately afterT1, or one time resource after T1. In other words, the UE transmittiming adjustment is not delayed or the adjustment is applied withminimal delay when there are two or more signals configured for uplinktransmissions with overlapping repetition periods. In another example,the transmission during T1 has precedence over the transmission in T2,and since T2 extends over the remaining time of T1, the UE can correctthe timing at the start of T1. But the UE would not be allowed tocorrect the timing at the onset of T2, since there would be a part of T1left after T2 had been completed.

Although not shown in the drawings, the proposed embodiments herein canalso include further embodiments. Further embodiments may be suitable inthe following situation. A wireless communication device 101 isreceiving a plurality of TACs from a network node (for example eNodeB)but does not take them into account immediately because of theconsiderations about the delay discussed above. Instead, the UE ratherremembers the TACs till a later point in time which is more suitable foruplink timing adjustment. There are at least the followingpossibilities:

-   -   1. Only the last received TA command is taken into account. The        earlier received TA commands are discarded. Thus, to the network        node (eNB) it is as though the earlier TA commands are lost.        With this approach, eNB does not really need to be aware that        the UE is discarding the earlier TA commands. In this        embodiment, the applying unit 205 is configured to only apply        the last received TAC, for example.    -   2. All TA commands (accumulated) take effect at the same time.        Here the UE sums all TA commands to be applied in one step. This        approach allows eNB to send several TA commands corresponding to        small timing adjustments over a period of time which then can        take effect at the appropriate time. This assumes that eNB is        aware that the UE is buffering the TA commands. In this        embodiment, the wireless communication device 101 further        includes summing unit 208 configured to sum the plurality of        TACs; and the applying unit 205 is configured to apply the        summed plurality of TACs, for example.    -   3. TA commands are accumulated to take effect stepwise at        appropriate different times. Here the TA adjustment is too large        to be applied in one step, so the UE sums all TA commands and        divides them into separate increments to be applied in several        steps, each increments being not greater than the maximum TA        adjustment possible/allowed. Here, too, the NW node needs to be        aware that the UE is buffering the TA commands. In this        embodiment, the wireless communication device 101 further        includes: a summing unit 208 configured to sum the plurality of        TACs; and a dividing unit 209 configured to divide the plurality        of TACs into a plurality of separate increments, each increment        being not greater than the maximum timing advance adjustment        allowed. The applying unit 205 is configured to apply the        plurality of increments as TAC in a plurality of processes        (steps), respectively.

FIG. 9 is a schematic block diagram showing an example of a network node900. FIG. 10 is a schematic block diagram showing one embodiment of awireless communication device 1000.

In some embodiments, the network node 900 may include but is not limitedto an Input/Output Interface (shown as I/O) 901, a processor (shown asPROC) 902, and a memory (shown as MEM) 903. In some embodiments, thewireless communication device 1000 may include but is not limited to anInput/Output Interface (shown as I/O) 1001, a processor (shown as PROC)1002, and a memory (shown as MEM) 1003.

The memory 903 and the memory 1003 may comprise a volatile (e.g. RAM)and/or non-volatile memory (e.g. a hard disk or flash memory). In someembodiments, the memory 903 and the memory 1003 may be configured tostore a computer program, which, when executed by the processor 902 andprocessor 1002, causes the processor to carry out any of the abovementioned methods. The combination of processor 902 or 1002 with such amemory 903 or 1003 may be referred to as a processing circuit; it willbe appreciated that when the memory 903 or 1003 stores a computerprogram for carrying out one or more of the techniques described herein,the processing circuit is thereby configured to carry out those one ormore techniques. In another embodiment, the computer program can bestored in a remote location for example computer program product (shownas PROGRAM) 904 and 1004, and accessible by the processor 902 and 1002via for example carrier 905 and 1005.

The computer program product can be distributed and/or stored on aremovable computer readable media, e.g. diskette, CD (Compact Disk), DVD(Digital Video Disk), flash or similar removable memory media (e.g.compact flash, SD secure digital, memorystick, miniSD, MMC multimediacard, smart media), HD-DVD (High Definition DVD), or Bluray DVD, USB(Universal Serial Bus) based removable memory media, magnetic tapemedia, optical storage media, magneto-optical media, bubble memory, ordistributed as a propagated signal via a network (e.g. Ethernet, ATM,ISDN, PSTN, X.25, Internet, Local Area Network (LAN), or similarnetworks capable of transporting data packets to the infrastructurenode).

The several embodiments discussed in detail above are described for LTE.However, the embodiments are applicable to any RAT or multi-RAT systems,where the UE receives and/or transmits signals (e.g. data) e.g. LTEFDD/TDD, WCDMA/HSPA, GSM/GERAN, Wi Fi, WLAN, CDMA2000, NR, etc. Thenetwork node could be configured for operation using more than one cell,e.g. using PCell, SCell, PSCell.

Although the method disclosed in this specification is exemplified forthe case when the communication takes place between a network node and aUE, the same method could also be applied when the communication occursbetween at least two nodes; node 1 and node 2.

Examples of a first node include NodeB, MeNB, SeNB, a network nodebelonging to MCG or SCG, base station (BS), multi-standard radio (MSR)radio node such as MSR BS, eNodeB, network controller, radio networkcontroller (RNC), base station controller (BSC), relay, donor nodecontrolling relay, base transceiver station (BTS), access point (AP),transmission points, transmission nodes, RRU, RRH, nodes in distributedantenna system (DAS), core network node (e.g. MSC, MME etc), O&M, OSS,SON, positioning node (e.g. E-SMLC), MDT, etc.

Examples of a second node include target device, device to device (D2D)UE, proximity capable UE (i.e., ProSe UE), machine type UE or UE capableof machine to machine (M2M) communication, PDA, PAD, Tablet, mobileterminals, smart phone, laptop embedded equipped (LEE), laptop mountedequipment (LME), USB dongles, etc.

In case of ProSe (also known as D2D, sidelink) operation, thecommunication takes place between two ProSe capable UEs. The ProSeoperation by a UE is in a half-duplex mode, i.e. the UE can eithertransmit ProSe signals/channels or receive ProSe signals/channels. TheProSe UEs can also act as ProSe relay UEs whose tasks are to relay somesignals between ProSe UEs, but also to other nodes (e.g. network node).There is also associated control information for ProSe, some of which istransmitted by ProSe UEs and the other is transmitted by eNBs (e.g.,ProSe resource grants for ProSe communication transmitted via cellulardownlink control channels). The ProSe transmissions may occur onresources which are configured by the network or selected autonomouslyby the ProSe UE. The ProSe transmissions (e.g. PSDCH) include several(e.g. 3) retransmissions that are transmitted on consecutive subframes.The retransmissions or repetitions are needed to achieve good SD-RSRPmeasurement performance. The SD-RSRP measurement is used to performProSe relay selection by ProSe UEs.

A ProSe UE that operates under the network coverage may follow thetiming of the network node while it employs retransmissions/repetitions.According to the current specification, the ProSe UE follows the TimingAdvance Command (TAC) if it is available. Absent the rule proposedherein on when to apply the received TAC, this may cause problems forthe receiving node, e.g. those UEs that perform measurement on thesetransmitted signals. In this case, the ProSe determines the number ofsubframes m that needs to pass until onset of a ProSe (sidelink)transmission period. If this number m exceeds or equals a number q, e.g.q=6 as in legacy LTE where the received TAC is applied, then the ProSeUE may apply the TAC in the first sidelink transmission period. If onthe other hand m is less than q, then the ProSe UE postpones theapplication of the TAC until the next sidelink transmissions period(i.e. that includes all retransmission on consecutive subframes) whoseonset is after subframe n+q.

It should be noted that the word “comprising” or “including” does notexclude the presence of other elements or steps than those listed andthe words “a” or “an” preceding an element do not exclude the presenceof a plurality of such elements. The invention can at least in part beimplemented in hardware, firmware or software. It should further benoted that any reference signs do not limit the scope of the claims, andthat several “means”, “devices”, and “units” may be represented by thesame item of hardware.

While the embodiments have been illustrated and described herein, itwill be understood by those skilled in the art that various changes andmodifications may be made, and equivalents may be substituted forelements thereof without departing from the true scope of the presenttechnology. In addition, many modifications may be made to adapt to aparticular situation and the teaching herein without departing from itscentral scope. Therefore, it is intended that the present embodimentsnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out the present technology, but that thepresent embodiments include all embodiments falling within the scope ofthe appended claims.

Abbreviation Explanation

-   BW Bandwidth-   CE Coverage enhancement-   CP Cyclic prefix-   DCI Downlink control information-   DFT Discrete Fourier transform-   DMRS Demodulation reference signal-   DRX Discontinuous reception-   eMTC Evolved MTC-   EUTRA(N) Evolved universal terrestrial radio access (network)-   FDD Frequency division duplex-   GERAN GSM EDGE radio access network-   GSM Global system for mobile communication-   HARQ Hybrid automatic repeat request-   HD-FDD Half-duplex FDD-   IoT Internet of things-   LTE Long term evolution of UMTS-   MAC Media access control-   MIB Master information block-   M-PDCCH Machine type PDCCH-   MTC Machine type communication-   NB-IoT Narrowband IoT-   NB-MIB Narrowband MIB-   NB-M-PDCCH Narrowband M-PDCCH-   NB-PBCH Narrowband PBCH-   NB-PDCCH Narrowband PDCCH-   NB-PDSCH Narrowband PDSCH-   NB-PSS Narrowband PSS-   NB-SSS Narrowband SSS-   NB-PUCCH Narrowband PUCCH-   NB-PUSCH Narrowband PUSCH-   NTA Non-time alignment-   OFDM Orthogonal frequency division multiplexing-   PA Power amplifier-   PBCH Physical broadcast channel-   PDCCH Physical downlink control channel-   PDSCH Physical downlink shared channel-   PRACH Physical random access channel-   PRB Physical resource block-   PSS Primary synchronization signal-   PUCCH Physical uplink control channel-   PUSCH Physical uplink shared channel-   RA Random access-   RAT Radio Access Technology-   RRC Radio resource control-   Rx Receive(r)-   SRS Sounding reference signal-   SSS Secondary synchronization signal-   TA Timing advance-   TAC Timing advance command-   TAG Timing advance group-   TDD Time division duplex-   Tx Transmit(ter)-   TTI Transmission time interval-   UE User equipment-   UL Uplink

What is claimed is:
 1. A wireless communication system comprising awireless communication device and a network node, the wirelesscommunication device operating in an enhanced coverage mode, theenhanced coverage mode comprising sequential repetition of messages sentfrom the wireless communication device to the network node, wherein thenetwork node includes a transmitter configured to send a Timing AdvanceCommand (TAC) to the wireless communication device; and wherein thewireless communication device includes: a receiver configured to receivethe TAC from the network node; and a processing circuit configured toadapt a time at which the TAC is applied, such that a time differencebetween the time at which the TAC is applied and a time at which the TACis received shall be greater than or equal to a specified time, and suchthat application of the TAC shall not occur during a period after afirst subframe of a repeated uplink transmission till the end of saidrepeated uplink transmission.
 2. The wireless communication system ofclaim 1, wherein the processing circuit is further configured to:determine a subframe n at which the TAC is received, and determine atime difference, in the form of the number of subframes m, between thesubframe n and a first subframe k of a first repeated uplinktransmission; decide whether application of the TAC in subframe n+qwould occur after the first subframe till the end of the first repeateduplink transmission and output a respective decision, wherein q standsfor the specified time, in the form of the number of subframes; andapply the TAC according to the decision.
 3. The wireless communicationsystem of claim 2, wherein if m is greater than or equal to q, the TACis applied in the first subframe k.
 4. The wireless communication systemof claim 2, wherein the wireless communication device further includes atransmitter configured to transmit only one uplink signal or at leasttwo uplink signals whose repetition periods do not overlap with eachother in time, and wherein the processing circuit is configured to adaptthe time at which the TAC is applied such that if m is less than q, theTAC is applied in a subframe s representing a first subframe of a firstrepeated uplink transmission period for which s satisfies s≥n+q.
 5. Thewireless communication system of claim 2, wherein the wirelesscommunication device further includes a transmitter configured totransmit at least two uplink signals whose repetition periods partlyoverlap with each other in time, and wherein the processing circuit isconfigured to adapt the time at which the TAC is applied such that theTAC is applied at a first subframe of a first repetition period of anyone of the at least two uplink signals that does not overlap in timewith a repetition period of the others of the at least two uplinksignals, said first repetition period fulfilling a criterion that a timedifference between reception of the TAC and start of the firstrepetition period is greater than q.
 6. The wireless communicationsystem of claim 5, wherein the transmitter is configured to transmitmultiple uplink signals with different repetition periods (Ta, Tb), andwherein the processing circuit is configured to align the repetitionperiods by shifting in time at least one of start or end points of therepetition periods (Ta, Tb), such that an overlapping time of therepetition periods (Ta, Tb) is maximized or single transmission of themultiple uplink signals is minimized.
 7. The wireless communicationsystem of claim 6, wherein the repetition periods (Ta, Tb) are alignedaccording to any one of the followings rules: aligning the repetitionperiods to start at the same time; aligning the repetition periods toend at the same time; aligning the repetition periods to start within acertain time duration Δ1; and aligning the repetition periods to endwithin a certain time duration Δ2.
 8. The wireless communication systemof claim 2, wherein q=6.
 9. The wireless communication system of claim1, wherein the wireless communication device receives a plurality ofTACs while unable or prohibited to take them into account immediately,and wherein the processing circuit is configured to only apply the lastreceived TAC.
 10. The wireless communication system of claim 1, whereinthe wireless communication device receives a plurality of TACs whileunable or prohibited to take them into account immediately, wherein theprocessing circuit is further configured to sum the plurality of TACsand to apply the summed plurality of TACs.
 11. The wirelesscommunication system of claim 1, wherein the wireless communicationdevice receives a plurality of TACs while unable or prohibited to takethem into account immediately, and wherein the processing circuit isfurther configured to: sum the plurality of TACs; and divide theplurality of TACs into a plurality of separate increments, eachincrement being not greater than a maximum timing advance adjustmentallowed; and apply the plurality of increments as TAC in a plurality ofprocesses, respectively.
 12. The wireless communication system of claim1, wherein the network node further includes a configuring unitconfigured to: configure the wireless communication device to transmitmultiple uplink signals with different repetition periods (Ta, Tb); andconfigure the wireless communication device to align the repetitionperiods by shifting in time at least one of the start or end points ofthe repetition periods (Ta, Tb), such that the overlapping time of therepetition periods (Ta, Tb) is maximized or single transmission of themultiple uplink signals is minimized.
 13. The wireless communicationsystem of claim 12, wherein the repetition periods (Ta, Tb) are alignedof any one of the followings rules: aligning the repetition periods tostart at the same time; aligning the repetition periods to end at thesame time; aligning the repetition periods to start within a certaintime duration; and aligning the repetition periods to end within acertain time duration.
 14. The wireless communication system of claim 1,wherein the network node further includes a processing circuitconfigured to generate a TAC to be used by the wireless communicationdevice, and wherein the transmitter of the network node is configured tosend the generated TAC to the wireless communication device.
 15. Amethod in a wireless communication device that operates in an enhancedcoverage mode, the enhanced coverage mode comprising sequentialrepetition of messages sent from the wireless communication device to anetwork node, the method comprising: receiving a Timing Advance CommandTAC from the network node; and adapting a time at which the TAC isapplied such that a time difference between the time at which the TAC isapplied and a time at which the TAC is received shall be greater than orequal to a specified time depending and such that application of the TACshall not occur during a period after a first subframe of a repeateduplink transmission till the end of said repeated uplink transmission.16. The method of claim 15, wherein the adapting further includes:determining a subframe n at which the TAC is received; determining atime difference, in the form of the number of subframes m, between thesubframe n and a first subframe k of a first repeated uplinktransmission; deciding whether application of the TAC in subframe n+qwould occur after the first subframe till the end of the first repeateduplink transmission, wherein q stands for the specified time, in theform of the number of subframes; and applying the TAC according to thedeciding.
 17. The method of claim 16, wherein if m is greater than orequal to q, the TAC shall be applied in the first subframe k.
 18. Themethod of claim 16, wherein the method comprises transmitting only oneuplink signal or at least two uplink signals whose repetition periods donot overlap with each other in time, and wherein applying the TACcomprises, if m is less than q, applying the TAC in a subframe srepresenting a first subframe of a first repeated uplink transmissionperiod for which s satisfies s≥n+q.
 19. The method of claim 16, whereinthe method comprises transmitting at least two uplink signals whoserepetition periods partly overlap with each other in time, and whereinapplying the TAC comprises applying the TAC at a first subframe of afirst repetition period of any one of the at least two uplink signalsthat does not overlap in time with a repetition period of the others ofthe at least two uplink signals, said first repetition period fulfillinga criterion that a time difference between reception of the TAC andstart of the first repetition period is greater than q.
 20. The methodof claim 19, wherein the method comprises transmitting multiple uplinksignals with different repetition periods (Ta, Tb) and further comprisesaligning the repetition periods by shifting in time at least one ofstart or end points of the repetition periods (Ta, Tb), such thatoverlapping time of the repetition periods (Ta, Tb) is maximized orsingle transmission of the multiple uplink signals is minimized.
 21. Themethod of claim 20, wherein the repetition periods (Ta, Tb) are alignedaccording to any one of the following rules: aligning the repetitionperiods to start at the same time; aligning the repetition periods toend at the same time; aligning the repetition periods to start within acertain time duration Δ1; and aligning the repetition periods to endwithin a certain time duration Δ2.
 22. The method of claim 16, whereinq=6.
 23. The method of claim 15, wherein the method comprises receivinga plurality of TACs while unable or prohibited to take them into accountimmediately, and wherein the method further includes only applying thelast received TAC.
 24. The method of claim 15, wherein the methodcomprises receiving a plurality of TACs while unable or prohibited totake them into account immediately, and wherein the method furtherincludes summing the plurality of TACs and applying the summed pluralityof TACs.
 25. The method of claim 15, wherein the method comprisesreceiving a plurality of TACs while unable or prohibited to take theminto account immediately; and wherein the method further includes:summing the plurality of TACs; dividing the plurality of TACs into aplurality of separate increments, each increment being not greater thana maximum timing advance adjustment allowed; and applying the pluralityof increments as TAC in a plurality of steps.
 26. The method of claim15, wherein the wireless communication device is an evolved Machine TypeCommunication (eMTC) device or Narrow Band Internet of Things (NB-IoT)device.
 27. The method of claim 15, wherein the wireless communicationdevice and the network node operate in a Half Duplex Frequency DivisionDuplex (HD-FDD) mode.
 28. The method of claim 15, wherein the wirelesscommunication device and the network node operate in CoverageEnhancement mode A or B, wherein in Coverage Enhancement mode A, onesignal is repeated up to 32 times during a repetition period, andwherein in Coverage Enhancement mode B, one signal is repeated up to2048 times during a repetition period.
 29. A method in a network node incommunication with a wireless communication device that operates in anenhanced coverage mode, the enhanced coverage mode comprising sequentialrepetition of messages sent from the wireless communication device tothe network node, the method comprising: configuring the wirelesscommunication device to transmit multiple uplink signals with differentrepetition periods (Ta, Tb); and configuring the wireless communicationdevice to align the repetition periods by shifting in time at least oneof start or end points of the repetition periods (Ta, Tb), such that anoverlapping time of the repetition periods (Ta, Tb) is maximized. 30.The method of claim 29, wherein the repetition periods (Ta, Tb) arealigned according to any one of the following rules: aligning therepetition periods to start at the same time; aligning the repetitionperiods to end at the same time; aligning the repetition periods tostart within a certain time duration; and aligning the repetitionperiods to end within a certain time duration.
 31. The method of claim29, wherein the method further includes: generating a Timing AdvanceCommand TAC to be used by the wireless communication device; and sendingthe TAC to the wireless communication device.
 32. A wirelesscommunication device that operates in an enhanced coverage mode, theenhanced coverage mode comprising sequential repetition of messages sentfrom the wireless communication device to a network node, wherein thewireless communication device includes: a receiver configured to receivea Timing Advance Command TAC from the network node; and a processingcircuit configured to adapt a time at which the TAC is applied, whereina time difference between the time at which the TAC is applied and atime at which the TAC is received shall be greater than or equal to aspecified time, and application of the TAC shall not occur during aperiod after a first subframe of a repeated uplink transmission till theend of said repeated uplink transmission.
 33. The wireless communicationdevice of claim 32, wherein the processing circuit is configured to:determine a subframe n at which the TAC is received, and determine atime difference, in the form of the number of subframes m, between thesubframe n and a first subframe k of a first repeated uplinktransmission; decide whether application of the TAC in subframe n+qwould occur after the first subframe till the end of the first repeateduplink transmission and output a respective decision, wherein q standsfor the specified time, in the form of the number of subframes; andapply the TAC according to the decision.
 34. The wireless communicationdevice of claim 33, wherein the processing circuit is configured toapply the TAC in the first subframe k, if m is greater than or equal toq.
 35. The wireless communication device of claim 33, wherein thewireless communication device further includes a transmitter configuredto transmit only one uplink signal or at least two uplink signals whoserepetition periods do not overlap with each other in time, and whereinthe processing circuit is configured to apply the TAC in a subframe srepresenting a first subframe of a first repeated uplink transmissionperiod for which s satisfies s≥n+q, if m is less than q.
 36. Thewireless communication device of claim 33, wherein the wirelesscommunication device further includes a transmitter configured totransmit at least two uplink signals whose repetition periods partlyoverlap with each other in time, the processing circuit is configured toapply the TAC at a first subframe of a first repetition period of anyone of the at least two uplink signals that does not overlap in timewith a repetition period of the others of the at least two uplinksignals, said first repetition period fulfilling a criterion that a timedifference between reception of the TAC and start of the firstrepetition period is greater than q.
 37. The wireless communicationdevice of claim 36, wherein the transmitter is configured to transmitmultiple uplink signals with different repetition periods (Ta, Tb), andthe processing circuit is further configured to align the repetitionperiods by shifting in time at least one of start or end points of therepetition periods (Ta, Tb), such that an overlapping time of therepetition periods (Ta, Tb) is maximized or single transmission of themultiple uplink signals is minimized.
 38. The wireless communicationdevice of claim 37, wherein the processing circuit is configured toalign the repetition periods (Ta, Tb) according to any one of thefollowing rules: aligning the repetition periods to start at the sametime; aligning the repetition periods to end at the same time; aligningthe repetition periods to start within a certain time duration Δ1; andaligning the repetition periods to end within a certain time durationΔ2.
 39. The wireless communication device of claim 33, wherein q=6. 40.The wireless communication device of claim 32, wherein the processingcircuit is configured to only apply the last received TAC in the eventthat the wireless communication device receives a plurality of TACswhile unable or prohibited to take them into account immediately. 41.The wireless communication device of claim 32, wherein the processingcircuit is configured to, in the event that the wireless communicationdevice receives a plurality of TACs while unable or prohibited to takethem into account immediately, sum the plurality of TACs and apply thesummed plurality of TACs.
 42. The wireless communication device of claim32, wherein the processing circuit is configured to, in the event thatthe wireless communication device receives a plurality of TACs whileunable or prohibited to take them into account immediately: sum theplurality of TACs; divide the plurality of TACs into a plurality ofseparate increments, each increment being not greater than a maximumtiming advance adjustment allowed; and apply the plurality of incrementsas TAC in a plurality of processes, respectively.
 43. The wirelesscommunication device of claim 32, wherein the wireless communicationdevice is an evolved Machine Type Communication (eMTC) device or NarrowBand Internet of Things (NB-IoT) device.
 44. A network node for use incommunication with a wireless communication device that operates in anenhanced coverage mode, the enhanced coverage mode comprising sequentialrepetition of messages sent from the wireless communication device tothe network node, the network node comprising processing circuitconfigured to: configure the wireless communication device to transmitmultiple uplink signals with different repetition periods (Ta, Tb); andconfigure the wireless communication device to align the repetitionperiods by shifting in time at least one of start or end points of therepetition periods (Ta, Tb), such that an overlapping time of therepetition periods (Ta, Tb) is maximized.
 45. The network node of claim44, wherein the repetition periods (Ta, Tb) are aligned according to anyone of the following rules: aligning the repetition periods to start atthe same time; aligning the repetition periods to end at the same time;aligning the repetition periods to start within a certain time duration;and aligning the repetition periods to end within a certain timeduration.
 46. The network node of claim 44, wherein the processingcircuit is further configured to generate a Timing Advance Command TACto be used by the wireless communication device, and wherein the networknode further comprises a transmitter configured to send the generatedTAC to the wireless communication device.